Pradeep metallurgical products offers unichrome c, a yellow chromatizing process, which is an efficient pre-treatment for aluminum and its alloys, by dip/spray processes. The unichrome c treatment deposits a uniform, amorphous, rainbow brown, chromate conversion coating. The intensity and the coating thickness depend upon the immersion period, composition of the metals, etc. The chromate conversion coating facilitates excellent corrosion resistance [more than 100 hrs on a 5% sodium chloride salt-spray test], and an improved bonding with the paints/powder coatings/organic coatings deposited on the metal. The chromatized components are then oven dried/air-dried and painted preferably within 24 hours. In the case of aluminum alloys, it is recommended to give a 5 minutes dip in a 5% solution of activator solution for the removal of the oxide scales and the rust spots. Unichrome-c is used at a concentration of 2.5-5 % w/v, for a dipping period of 5-10 min at room temperature. Periodic checking of ta/fa and water rinsing and drying after chromatizing are recommended.
